The present invention relates to the field of short distance wireless telephony, and in particular to an apparatus that links a wireless headset with a Central Office telephone line.
FIG. 1 illustrates the prior art configuration most commonly used for hands-free telephony at the consumer level. A cordless phone base 102 is connected to wall jack 101 and thence to a Central Office telephone line. For hands-free operation, it is necessary that the cordless phone handset 103 be equipped with a headset jack with the customary 3 wire interface to a corded headset 104. Three connections, i.e. mic, earphone and common are brought respectively to the tip, ring and sleeve terminals of a 2.5 mm plug at the end of the headset cord. A ringer is fitted in both the base and the handset whereas a keypad with several buttons for going off hook, dialing and terminating a call is found on the handset. The user of this prior art system is twice encumbered, first by having to deal with the headset cord in awkward situations and then by having to raise the handset from waist level in order to operate the buttons.
The cost of such cordless phones today is low and the FCC spectrum allocations sufficient for the needs of the broad consumer market. Newer cordless handsets may come equipped with a headset jack for the added facility of hands-free operation once a headset is plugged into this jack on the RF handset. The headset may either be bundled with the phone or it may be sold separately. Such a headset is likely to be configured for positioning over the head via a headband or over the ear via an earhook and fitted with a receiver at the ear and a microphone boom toward the mouth. When a cordless handset is thus connected to a headset, the user will likely clip the handset to his or her belt and a cord from the headset will span the distance from the waist to the ear. Clearly then the microphone and receiver in the cordless handset are made redundant when such a headset is employed. Furthermore the handset is physically larger than it would be if it had no built-in mic and receiver.
Cordless headset phones are available to satisfy the requirement for cordless telephony without the added bulk of redundant mic and receiver transducers in the handset. An exemplary product is the CT-12 Cordless Headset Telephone by Plantronics, Inc. The package for CT12 includes a base unit, a “remote” module with belt clip and a headset with cord. The base connects to a CO phone line and to AC power and also provides for charging of the batteries in the “remote.” It is evident that although this product is suitable for hands-free telephony over a RF link, it fails to offer a wire-free solution and requires that the user wear a belt or find other means for carrying the “remote.” The headset cord from the CT12 belt-worn “remote” module to the ear will likely snag when the wearer interacts with children or performs household activities.
Other headsets are wireless and self contained in order to overcome the limitations of a beltpack with a cord to the headset. An exemplary product is the XLT Headset by Hello Direct, Inc. However, the XLT is not a true telephone but has a base unit which must connect to the handset port of a preinstalled corded telephone. Said differently, the XLT is a wireless headset substituting for the wired handset on a particular telephone set. The XLT user has to physically access, i.e. touch, this telephone for going off hook, dialing etc. Handset port wiring of telephone sets is not standardized. The receive and transmit pair connections from the handset to the phone are likely to vary among manufacturers. Therefore a complex “learning” process must be invoked in order to configure the interface to the handset port correctly.
RF headsets without base units are also available. When those are based on the Bluetooth specification instead of a proprietary RF link, they are interoperable with other Bluetooth enabled devices such as cellular handsets, computers and automobiles. Such Bluetooth headsets however are not connectable to a Central Office line unless they are optionally added to a system with a dedicated Bluetooth base unit and a Bluetooth handset with facilities for dialing, ringing, charging of the handset batteries etc. An exemplary product is the Olympia 2.4 GHz 2-Line Bluetooth Cordless Data Phone. It will be appreciated that Olympia is a complex system that must be purchased and installed before a user can enjoy the benefits of cord-free hands-free operation and do so only after a Bluetooth headset is added to the system.